Airworthiness Directive · Amendment 39-13765 · Boeing Model 747 Series Airplanes
Boeing Model 747 Series Airplanes
Superseded. A later AD replaced this one: AD 2009-04-06. Comply with the one in force.
All Model 747 series airplanes; certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to all Model 747 series airplanes, that requires repetitive detailed inspections of the aft pressure bulkhead for indications of "oil cans" and previous oil can repairs, and corrective actions, if necessary. An oil can is an area on a pressure dome web that moves when pushed from the forward side. This action is necessary to detect and correct the propagation of fatigue cracks in the vicinity of oil cans on the web of the aft pressure bulkhead, which could result in rapid decompression and overpressurization of the tail section, and consequent loss of control of the airplane. This action is intended to address the identified unsafe condition.
Note 1: This AD refers to certain portions of a Boeing service bulletin for inspections and repair information. In addition, this AD specifies requirements beyond those included in the service bulletin. Where the AD and the service bulletin differ, the AD prevails.
To detect and correct the propagation of fatigue cracks in the vicinity of “oil cans” on the web of the aft pressure bulkhead, which could result in rapid decompression and overpressurization of the tail section, and consequent loss of control of the airplane, accomplish the following:
(a) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2482, dated October 3, 2002.
(b) Prior to the accumulation of 30,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever is later, perform a detailed inspection of the aft pressure bulkhead for indications of oil cans and previous oil can repairs, in accordance with the service bulletin.
Note 2: For the purposes of this AD, a detailed inspection is “an intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors magnifying lenses, etc. may be necessary. Surface cleaning and elaborate procedures may be required.”
(c) If no indication of an oil can is found and no indication of a previous oil can repair is found during the detailed inspection required by paragraph (b) of this AD, repeat the detailed inspection thereafter at intervals not to exceed 2,000 flight cycles.
(d) If any indication of an oil can is found during the detailed inspection required by paragraph (b) or (c) of this AD, before further flight, perform an eddy current inspection of the web around the periphery of the oil can indication for cracks, as shown in Figure 3 of the service bulletin.
(e) If no crack is found during the eddy current inspection required by paragraph (d) of this AD, do the actions specified in paragraph (e)(1) or (e)(2) of this AD, as applicable.
(1) For the oil can that meets the allowable limits specified in the service bulletin: Repeat the eddy current inspection specified in paragraph (d) of this AD thereafter at intervals not to exceed 1,000 flight cycles. As an option, repair the oil can in accordance with paragraph (e)(2) of this AD.
(2) For the oil can that does not meet the allowable limits specified in the service bulletin: Before further flight, repair the oil can in accordance with the service bulletin. If the repair eliminates the oil can, accomplishment of this repair constitutes terminating action for the repetitive eddy current inspection requirements of paragraph (e)(1) of this AD for that location only. However, the repetitive detailed inspection required by paragraph (c) of this AD is still required. If any oil can remains after the repair, repeat the eddy current inspection specified in paragraph (d) of this AD thereafter at intervals not to exceed 1,000 flight cycles.
(f) If any previous oil can repair is found during the detailed inspection required by paragraph (b) or (c) of this AD, before further flight, do a detailed inspection of the web for cracks and oil cans, as shown in Figure 4 or Figure 5 of the service bulletin, as applicable.
(1) If no crack and no oil can are found, repeat the detailed inspection in accordance with paragraph (c) of this AD.
(2) If any oil can is found, before further flight, do the eddy current inspection for cracks, as shown in Figure 3 of the service bulletin. If no crack is found during the eddy current inspection required by this paragraph, do the actions specified in paragraph (e)(1) or (e)(2) of this AD, as applicable, at the time specified in the applicable paragraph.
(g) If any crack is found during any inspection required by this AD, before further flight, repair in accordance with the service bulletin. If any crack or damage exceeds limits specified in the service bulletin and the service bulletin specifies to contact Boeing for appropriate action: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD.
(h) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, FAA, is authorized to approve alternative methods of compliance for this AD.
(i) Unless otherwise specified in this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2482, dated October 3, 2002. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
